1. Field of the Invention
This invention relates generally to segmented storage logging and controlling and more particularly to a system and method for the efficient maintenance of segments and segment portions of a segmented serial storage device for the reading and writing of text pages thereon as well as a plurality of stored directories thereon indicating utilization and availability of storage portions.
2. Description of the Prior Art
Described in U.S. Pat. Nos. 3,753,239 and 3,781,813 is a technique for logging the utilization of storage blocks on a serial bulk memory and assigning blocks for storage of new and revised text pages to eliminate the burden to a text processing system operator of having to keep track of the logical sequence of storage blocks that correspond to pages of a document being prepared or revised. The log was recorded onto a block at the beginning of the memory at the completion of each storage or deletion operation.
One of the shortcomings of this system is that an excessive amount of accessing time may be required after a storage operation to access the storage block on which the log is to be written or rewritten, which may, for example, be physically located a relatively large distance away from the storage block on which the text storage operation took place. Wear of the electromechanical accessing components is also increased by the great number of repeated, physically long distance, accessing moves that are required by the accessing mechanism in the described system. Nor was the possibility addressed in these patents that errors might occur in reading the log from the storage or writing the log onto the storage. Apparently, if an error occurred in reading the log from the storage, data on the storage could be lost such that extensive rekeying by the operator would be necessary, not because of errors in the recorded text data on the storage, but because of errors in the log.
The above patents disclose a log having a tape log section thereof in which an indicator bit was provided to determine the used or unused status of each tape block in the storage. If a hard error (defect in the tape, itself that prevents recording or reading) was found in a block, the block was logged as utilized. Thus, there was no distinction as to whether the block, logged as utilized, stored valid text data or was not to be used because of errors.
Neither did the above patents address situations that occur when text data cannot be successfully read from the storage into the text processing system because of reading errors. Suppose, for example, that two pages (blocks), from the tape were read into the text processing memory, but not reviewed by the operator. Assume that no valid text data was read from the second block such that this page is not in the memory. If the operator re-stored this text without reviewing the text to realize that some of the text was missing, the log would be updated to reflect that a page of text was deleted from the job, when, in fact, the operator needed to maintain storage area to rekey the lost text.
It would, therefore, be advantageous to provide a segmented bulk storage logging and controlling system and method which overcomes the above shortcomings of the prior art to provide increased utilization of the storage capability of the storage device due to improved controlling techniques and increased integrity of the data and faster access of the data due to improved logging techniques.